This invention relates to activation of mobile stations in a cellular network system and, more particularly, to a method of providing subsidy protection for a cellular operator.
Under present practices in the United States, cellular network system operators often subsidize the price of a mobile station as part of a long-term service agreement. Therefore, the operators prefer to tie operation of the mobile station to the operators"" cellular network system.
Protection of the operators"" subsidy has proven straightforward in the United States"" cellular network systems. This was done by downloading an international mobile station identity (IMSI) at the time of activation. The IMSI is a unique number that is allocated to each mobile subscriber. The particular mobile station is then personalized with the downloaded IMSI which is used thereafter for receiving and transmitting cellular calls.
The global system for mobile communications (GSM) uses a removable subscriber identity module (SIM) card. The SIM card stores an IMSI value, which is referred to in the GSM system as an international mobile subscriber identity. The SIM cards are conventionally pre-programmed to include the IMSI. Thus, a cellular operator typically purchases a supply of SIM cards. The mobile stations themselves do not include information that identifies the subscriber. Instead, the mobile station is a shell until the SIM card is installed. This practice makes it more difficult for an operator to provide subsidy protection. This is particularly true since the SIM card could be installed in different phones for operation even if the phone were not provided by the particular operator.
There exists a desire to utilize SIM card technology in cellular network systems presently used in the United States. However, the operators also desire the ability to download the subscriber information over the air to facilitate distribution and provisioning of mobile stations in the operator""s cellular network system. These two desires have heretofore been incompatible.
The present invention is directed to overcoming the problems discussed above in a novel and simple manner.
In accordance with the invention there is provided the method of activating a mobile station used in a cellular network system to provide subsidy protection for a cellular operator. The method comprises the steps of installing a subscriber identity module (SIM) in the mobile station, the SIM having an IMSI file and storing first indicia uniquely identifying the cellular operator, the mobile station storing second indicia uniquely identifying the cellular operator; comparing the first indicia to the second indicia to determine if the SIM and the mobile station are valid for the cellular operator; and if the SIM and the mobile station are valid, then storing a mobile identity number in the IMSI file of the SIM.
It is a feature of the invention that the mobile station comprises a mobile station for use in a TDMA cellular network system.
It is another feature of the invention that the first indicia comprises a mobile country code and a mobile network code included in the IMSI file. A remainder of the IMSI file is initially blank. The second indicia comprises a mobile country code and a mobile network code and the SIM and the mobile station are valid if the first indicia is identical to the second indicia.
In accordance with another aspect of the invention, the first indicia comprises an equipment serial number (ESN). The second indicia comprises a range of ESNs and the comparing step determines if the first indicia ESN is within the range of the second indicia.
It is still another feature oft he invention that the storing step comprises downloading the mobile identity number via the cellular network system.
It is disclosed in accordance with a further aspect of the invention the method of activating a mobile station used in a TDM cellular network system to provide subsidy protection for a cellular operator. The method comprises the steps of installing a subscriber identity module (SIM) in the mobile station, the SIM having an IMSI file storing first indicia uniquely identifying the cellular operator; the mobile station storing second indicia uniquely identifying the cellular operator; comparing the first indicia to the second indicia to determine if the SIM and the mobile station are valid for the cellular operator; and if the SIM and the mobile station are valid, then storing a mobile identity number in the IMSI file of the SIM.
Further features and advantages of the invention will be readily apparent from the specification and from the drawings,